This invention relates to a line illumination device comprising
a carrier,
a plurality of tubular fluorescent lamps in linear arrangement which each have end portions with respective lamp caps,
lampholder pairs which are connected to the carrier and in each of which a respective lamp is held with its lamp caps.
The invention also relates to a mounting member suitable for use in said device.
Such a line illumination device is known from, inter alia, DE-GM-1 989 496.
The known device has the disadvantage that the light line formed during operation has interruptions because the lamp caps and the lampholders radiate no light. In addition, the dark zones present at the area of a lamp cap / a lampholder / a lampholder / a lamp cap are bounded on either side by zones which radiate only a small quantity of light. These zones are caused by the fact that the discharge in the lamps extends only between the electrodes positioned near the ends of the lamp vessel, but not also from each electrode to the adjacent end. The differences in brightness and the differences in illuminance caused by these dark and weakly luminous zones are unpleasant.
According to the Utility Model cited, these differences are reduced in that the lamps are made to overlap one another partly. It is possible then to position the lamps alternately in a first and in a second, parallel line. Disadvantages of this solution are that interruptions remain which cause unpleasant differences, that the device has a greater lateral dimension and inevitably has a meandering pattern. As a result, an illuminated field in addition gets the unevenness of a wavy pattern.
Another overlapping arrangement of the lamps known from the said Utility Model has a sawtooth shape. This arrangement has the same disadvantages as the previous one. Added to this is another disadvantage, i.e. a field illuminated by the lamps has a pattern which is to a high degree determined by the diagonal direction which the lamps have.
DE 284 537 discloses a line illumination device in which prismatic, mirroring bodies are positioned on each of the lampholders, which bodies throw the light coming from the lamps in a direction away from the carrier. The result is that light seems to be coming from the lampholder. This measure, however, only effects a small reduction in the unevenness of the illuminance and of the brightness of the light line. In fact, the prismatic bodies receive only that small fraction of light which is radiated by the lamp ends at a great angle to the perpendicular of these ends, while these ends already have a lower brightness than portions farther away from the ends. The prismatic bodies do not throw light towards the carrier.